Myriad presents studies showing that its rheumatoid arthritis test can predict patient response to drugs

Myriad Genetics ($MYGN) touted three studies at the meeting of the American College of Rheumatology in San Francisco showing that its Vectra DA diagnostic for measuring the severity of rheumatoid arthritis (RA) can help guide patient selection for biologic or nonbiologic drugs by predicting their response to the various therapies and treatment strategies.

The blood test aggregates molecular information about 12 biomarkers into a single score from zero to 100, with a score above 44 being indicative of high disease activity, said Crescendo Chief Medical Officer Dr. Elena Hitraya in an interview.

Multiple biomarkers are needed because of the diseases' heterogeneity, she said: "TNF (tumor necrosis factor) may drive the disease significantly in some patients, but other cytokines and growth factors hormones are involved in driving the disease as well. So if you're trying to assess one single biomarker you're probably not going to get a clear picture of the pathological changes and what's driving the disease."

The immunosuppressant methotrexate is the first-line therapy for rheumatoid arthritis, but it isn't always effective. "At this point physicians need to make a choice," Hitraya said. "The options that they have is you adding a synthetic biological drug, or adding a biological drug, which is most often anti-TNF."

To that end, one study of 157 nonresponders to three months of first-line methotrexate therapy found that those who had a low Vectra DA score were more likely to respond to a triple therapy of nonbiologics, while patients with a high level of disease activity fared better on anti-TNF biologics. It was conducted by a team of Swedish researchers and academics from the Helsingborg Hospital, Lund University and the Karolinska Institute in collaboration with Crescendo. 

Currently, biologics for RA have a nonresponse rate of around 30% to 40%, Hitraya said.

In addition to improving outcomes, the diagnostic (described as a "molecular thermometer") improves the efficiency of the healthcare system, for nonbiological therapies (often generic) cost less than biologics, which run about $30,000 per year, she said.

Two other studies presented provide guidance to physicians about discontinuation of therapy. One found that patients with a high Vectra DA score and positive results on a single-biomarker test had relapse rate of 76%, compared to 32% among those with a low Vectra DA score. And a third study found that high Vectra DA scores were correlated with relapse of the disease in patients tapering their drug therapies.

Hitraya explained that Vectra DA can help identify patients who show clinical improvement but continue to have high levels of underlying disease activity, making them vulnerable to relapses or flares.

Although single-biomarker tests for RA are sometimes used, Hitraya said they are not very specific to the disease and can be elevated by other conditions that cause inflammation.

Crescendo Bioscience President Bernie Tobin said during the interview that 40% of rheumatologists use Vectra DA each month. The company is planning to enroll patients in a prospective randomized study next year focused more squarely on health economics and cost-effectiveness in a bid to win over private payers, whose support is crucial to widespread adoption, he said, adding that Medicare reimburses two Vectra DA tests per patient per year.

The diagnostic is a crucial plank of Myriad's diversification strategy following the 2013 Supreme Court decision that ended its monopoly on BRCA testing. Myriad acquired Vectra DA with its takeover of Crescendo Biosciences for $270 million in 2014.

Myriad CEO Mark Capone previewed the studies during the company's Nov. 3 earnings call. In addition, he said the diagnostic has a worldwide addressable market of $3 billion, including $600 million in the U.S. Overall, 38,000 Vectra DA tests were conduct during the quarter, resulting in revenues of $11.4 million.

The test is now orderable through LabCorp's ($LH) more than 1,700 patient service centers, Capone said.

Myriad is arguing against changes to CMS' preliminary Clinical Lab Fee schedule that would result in a 60% decrease in Vectra DA if finalized. "Myriad, along with an extensive array of extremely concerned stakeholders, including physicians, patients, legislators, and the majority of the precision medicine industry, have commented on this preliminary recommendation," Capone said. "We anticipate final revisions will be published in November when the calendar year 2016 clinical laboratory fee schedule is published."

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